// mixin:混合复用，后面可以接参数
@mixin alert($text-color,$background) {
  color: $text-color;
  background-color: $background;
  a {
    color: darken($text-color, 10%);
  }
}

.alert-warning {
  @include alert(#8a6d3b, #fcf8e3);
}

.alert-info {
  @include alert($background: #d9edf7, $text-color: #31708f)
}
